As shown in FIG. 1, a conventional crown button of the cap is generally made of a metal material by punching and pressing and is composed of a top piece 11, a guide piece 12, a receiving-piece 13, a nail 14, and a base seat 15. A male member is formed by the nail 14 which is disposed in the base seat 15 such that the nail 14 is located by a press portion 15a. The guide piece 12 is fastened to the receiving piece 13. The top piece 11 is covered with a piece of cloth 16 having an end extending to reach the inner side of the top piece 11 such that the combining bodies of the guide piece 12 and the receiving seat 13 are fitted into the top piece 11 so as to press and locate the cloth 16 to form a female member, which is disposed on the crown top of a cap. In the meantime, the male member is placed at the bottom of the cap before the male member is exerted on by a pressure of a greater magnitude. An insertion needle 14a is inserted into a guide slot 13a of the receiving seat 13 such that the needle is caused to curve along the arcuate inner wall of the guide piece 12. As a result, the male and the female members are fastened and located at the crown top of a cap.
Such a prior art cap crown button as described above is high in production cost and installing cost. As a result, the cap crown button of a plastic material was introduced. As shown in FIG. 2, the plastic crown button comprises a female retaining body 21, a fastening element 22 and a male retaining body 23. The female retaining body 21 is provided with a hollow projection 21a having therein an inverted bevel hook 21b. The male retaining body 23 is provided centrally with a nail 23a having a circular groove 23b. The female retaining body 21 is wrapped with a decorative cloth before being fastened by the fastening element 22 to the center of the crown top of a cap. The female retaining body 21 is held by the nail 23a of the male retaining body 23.
Such a plastic crown button as described above is defective in design in that the female retaining body 21 can not be made easily, and that the effect of fastening the female retaining body 21 with the male retaining body 23 is relatively poor, and further that the wrinkles in the decorative cloth wrapping the female retaining body 21 undermine the esthetic effect of the crown button, and still further that the female retaining bodies 21 are bound to be so crammed in the automatic feeding device of a riveting machine that they can not be fed one by one into the riveting machine with precision.